Motor stator and molded motor

ABSTRACT

A motor stator is disclosed. Each of a first phase, second phase and third phase of three-phase winding has multiple toroidal coils and crossover wires connecting the coils. The crossover wire of the first phase runs inside the second phase coil and the third phase coil. The crossover wire of the second phase runs over the first phase coil with a guide by guide posts and runs inside the third phase coil. The crossover wire of the third phase runs over the first phase coil and the second phase coil with a guide by the guide posts.

This application is a continuation of U.S. patent application Ser. No.12/302,648, filed Oct. 7, 2009, which is a U.S. National PhaseApplication of PCT International Application PCT/JP2007/060426, filedMay 22, 2007, the entire disclosures of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a motor stator to be used in homeappliances, and it also relates to a molded motor employing the samestator.

BACKGROUND ART

In recent years, motors to be employed in home appliances have beenswitched from conventional ones to brushless motors in order to obtainhigher efficiency from the standpoint of energy saving. This markettrend has been accompanied by giving attention to a twin-rotor typethree-phase brushless motor which includes magnet-rotors both inside andoutside an annular stator. (disclosed in e.g. patent document 1 andpatent document 2)

When the annular stator is provided with a toroidal winding, an annularstator core is generally split into equal halves. Then as shown in FIG.12, first phase coil 60 is wound with a space remaining for a secondphase coil, and then the second phase coil is wound on the space. Acrossover wire is provided between the first phase coil and the secondphase coil, so that it is afraid that the crossover wire sometimestouches the coils of different phases. An insulating procedure thus mustbe taken, such as sticking an insulating tape to both of first phasecoil 60 and the crossover wire of the first phase, before the secondphase coil is wound although the tape sticking is a cumbersome work. Aninsulating space is thus desirably prepared between the coil and thecrossover wire for eliminating the tape sticking job.

The stator core provided with toroidal windings is resin-molded, ingeneral, before it is completed as a stator of a motor. The structure ofthe stator core thus must withstand a high pressure of molding resin andhold an insulating space between the coil and the crossover wire. Patentdocument 3, for example, discloses a groove for accommodating acrossover wire in order to prevent the crossover wire from touching thecoil.

Patent document 1: Unexamined Japanese Patent Application PublicationNo. 2005-333727

Patent document 2: Unexamined Japanese Patent Application PublicationNo. 2006-101656

Patent document 3: Unexamined Japanese Patent Application PublicationNo. H05-184092

DISCLOSURE OF INVENTION

The stator of a motor of the present invention comprises the followingelements:

-   -   a stator core including an annular yoke, and teeth at least one        of the inside or the outside of the yoke;    -   an insulating cover including a plurality of grooves and a        plurality of guide posts, and covering the stator core; and    -   a three-phase winding wound on the stator core in a toroidal        winding manner via the insulating cover.        Each of a first phase, a second phase, and a third phase of the        three phase winding includes a plurality of toroidal coils and        crossover wires connecting the coils. A crossover wire of the        first phase runs through the groove of the insulating cover, and        runs inside the coils of second and third phases. A crossover        wire of the second phase runs over the first phase coil with a        guide by the guide posts of the insulating cover, and then runs        through the groove and inside the third phase coil. A crossover        wire of the third phase runs over the coils of the first and        second phases with a guide by the guide posts. The foregoing        structure allows holding the insulating space between the coils        and the crossover wires even if a high pressure of molding resin        is applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first phase coil wound on a stator core.

FIG. 2 shows a second phase coil wound on the stator core.

FIG. 3 shows a perspective view in part of the stator core on which afirst phase coil and a second phase coil are wound.

FIG. 4 shows a perspective view of the stator core on which the coils ofthe first, second and third phases are wound.

FIG. 5 shows a sectional view of a guide post including a partition.

FIG. 6 shows a stator core set in a metal mold.

FIG. 7 shows a winding guide provided at a slot opening.

FIG. 8 shows a wire-end holder provided to an insulating cover.

FIG. 9 shows a cover of a groove which accommodates a crossover wire.

FIG. 10 shows insulation provided to the crossover wire.

FIG. 11 shows another insulation provided to the crossover wire.

FIG. 12 shows a conventional toroidal winding.

DESCRIPTION OF REFERENCE MARKS

-   -   1 stator core    -   2 yoke    -   3 inner teeth    -   4 outer teeth    -   5 insulating cover    -   6 thicker section    -   7 guide post    -   8 partition    -   11, 12, 13 first phase coil    -   14, 15 crossover wire of first phase    -   16 groove    -   17 slot opening    -   18 winding guide    -   19 holder    -   21, 22, 23 second phase coil    -   24, 25 crossover wire of second phase    -   26 groove    -   27 coil end    -   28 groove cover    -   29 insulating sheet clip    -   30 insulating sheet    -   31, 32, 33 third phase coil    -   34, 35 crossover wire of third phase    -   50 insulating space

DESCRIPTION OF PREFERRED EMBODIMENT

An exemplary embodiment of the present invention is demonstratedhereinafter with reference to the accompanying drawings. As shown inFIG. 1, one of stator core divided into equal halves, hereinafterreferred to as stator core 1, includes inner teeth 3 and outer teeth 4at both sides of yoke 2. Stator core 1 is covered with insulating cover5. A first phase coil, second phase coil and third phase coil aresequentially wound in a toroidal winding manner on stator core 1 atrespective slots between the teeth. The winding steps are detailedhereinafter.

First, as shown in FIG. 1, first phase coils 11, 12, 13 are wound onstator core 1 sequentially via crossover wires 14 and 15 which connectthe coils. Next, as shown in FIG. 2, second phase coils 21, 22, 23 arewound sequentially on stator core 1 via crossover wires 24 and 25.Crossover wire 24 runs over first phase coil 12, and crossover wire 25runs over first phase coil 13. Third phase coils 31, 32, 33 are woundsequentially at slots remaining unoccupied in FIG. 2 (refer to FIG. 4).Crossover wires 34, 35 of the third phase run over the coils, alreadywound, of the first and second phases. The crossover wires of therespective phases thus cross with the coils of other phases under orabove the coils.

FIG. 3 shows a perspective view in part of stator core 1 on which firstand second phase coils are wound. Insulating cover 5 includes grooves 16and 26 at thicker section 6 where the third phase coils are to be wound.Crossover wire 14 of the first phase is accommodated in groove 16, andcrossover wire 24 of the second phase is accommodated in groove 26.Insulating cover 5 further includes guide posts 7. Crossover wire 24runs through groove 26, and then, when it runs over first phase coil 12,it is guided by guide post 7 such that it maintains a predeterminedinsulating space 50 from first phase coil 12.

FIG. 4 shows a perspective view of stator core 1 on which the first,second and third phase coils are wound. Crossover wires 34, 35 areguided by guide posts 7 such that they maintain a predeterminedinsulating space from the first phase and second phase coils. Guideposts 7 are placed both at inner wall side and outer wall side of statorcore 1 so that the crossover wires can run separately along the innerside and the outer side of stator core 1. This structure allowspreventing the crossover wires from touching to each other. In FIG. 4,crossover wire 34 runs along the inner side of stator core 1 separatelyfrom wire 24 which runs along the outer side of stator core 1. In asimilar manner, crossover wire 25 inner side of stator core 1 isseparated from crossover wire 35 outer side of stator core 1.

If the crossover wires cannot be placed separately due to some reason,guide post 7 including partition 8 shown it sectional view in FIG. 5 isused. Since partition 8 separates the crossover wires, this structureallows preventing the crossover wires from touching to each other whenthis guide post 7 guides the crossover wires of different phases.

Stator core 1 including the toroidal coils is molded with resin to becompleted as a stator of a motor. FIG. 6 shows stator core 1 set inmetal mold 40. It is essential for the coils and the crossover wires ofstator core 1 not to be deformed by a high pressure of resin flowsupplied from mold gate 41 in order to maintain the predeterminedinsulating space therebetween.

Measures taken against the pressure of the resin flow are to separatethe crossover wire from the coils of different phases. For instance, acrossover wire running under a coil can be protected from the pressureof resin flow by the coil. When a crossover wire runs above the coil, anarrower interval between the guide posts will minimize a deviation ofthe crossover wire due to the resin flow.

As shown in FIG. 7, slot opening 17 is provided with winding guides 18,which guide the wire to opening 17 when the wire is wound as well ashold coil 20 when stator core 1 is molded for preventing coil 20 frombeing deformed by the pressure of the resin flow.

Thermosetting resin is preferably used for molding. The stator inaccordance with this embodiment of the present invention can be used ina molded motor. To be more specific, the stator of this embodiment canbe used in a molded motor at its motor frame which is molded ofthermosetting resin. During the molding, when a high pressure ofthermosetting resin is applied, the structure of this molded motorallows maintaining the insulating space between the coils and thecrossover wires.

Improvements of the stator core to a job in the steps of winding and toa reliability of insulation between phases of three-phase windings aredescribed hereinafter with reference to FIG. 8-FIG. 11.

During the step of winding the first phase coil, second phase coil, andthird phase coil sequentially on the stator core, coil ends 27 ofrespective coils must be fixed to somewhere in order to prevent thecoils from loosening. As shown in FIG. 8, projecting holder 19 isprovided on insulating cover 5 at the vicinity of the coil end, and coilend 27 is tied to holder 19 so that the coil can be prevented fromloosening.

As shown in FIG. 9, cover 28 is provided to an inner wall of groove 16(refer to FIG. 3) of insulating cover 5 so that cover 28 can hold thecrossover wire within groove 16 and prevents the crossover wire fromapproaching to the coil wound on thicker section 6.

FIG. 10 does not show thicker section 6 or groove 16 in insulating cover5 although they are shown in FIG. 9. Insulating sheet 30 is mounted onthe crossover wires for insulating them from the coils. Since there isno thicker section 6, the thickness of the stator is reduced. Insulatingsheet 30 can be mounted with ease by adhesive or by sheet clips 29provided on insulating cover 5.

As shown in FIG. 11, the crossover wires can be accommodated inshallower groove 16, and then insulating sheet 30 can be mountedthereon.

Industrial Applicability

A stator of the present invention is highly reliable about theinsulation between the phases of three-phase windings, so that thestator can be used not only in brushless motors but also in inductionmotors.

1. A motor stator comprising: a stator core including an annular yokeand teeth provided to at least one of an inside of the yoke and anoutside of the yoke; an insulating cover which covers the stator coreand includes at least one guide post; and three-phase windings wound onthe stator core in a toroidal winding manner via the insulating cover,wherein each of a first phase, a second phase and a third phase includesa plurality of coils wound in the toroidal manner and a crossover wireconnecting the coils, and wherein a crossover wire of at least one ofthe first phase, the second phase, and the third phase runs around theat least one guide post such that (i) an insulating space is formedbetween the crossover wire and a coil of another one of the first phase,the second phase, and the third phase and (ii) the crossover wire doesnot pass between the coil of the other one of the first phase, thesecond phase, and the third phase and the stator core.
 2. The motorstator of claim 1, wherein the stator core is circumferentially dividedinto equal halves.
 3. The motor stator of claim 2, wherein theinsulating cover includes a projecting holder for holding a coil end. 4.The motor stator of claim 1, wherein the guide post is one of aplurality of guide posts that are disposed on an outer side and an innerside of the insulating cover so that the crossover wires guided by theguide posts can run separately along the outer side and the inner side.5. The motor stator of claim 1, wherein the guide post is one of aplurality of guide posts that include a partition which separates thecrossover wires.
 6. The motor stator of claim 1, wherein the insulatingcover includes a winding guide formed at formed on both circumferentialsides of a slot opening.
 7. The motor stator of claim 1, wherein theinsulating cover includes a groove cover formed on an outer surfacethereof.
 8. The motor stator of claim 1, wherein the crossover wire runsover the insulating cover, and an insulating sheet is disposed on thecrossover wire, and the plurality of coils wound in the toroidal windingmanner is disposed on the insulating sheet.
 9. A molded motor comprisinga motor frame, which includes the motor stator as defined in claim 1 andis molded of thermosetting resin.